Jazz is the only truly American music genre. African Americans living in the Midwest combined the diverse rhythms of their ancestors with musical instruments from the European heritage of white Americans. The resulting music--jazz--became a cultural phenomenon that has spread around the globe and rippled through history to influence the modern music we hear on the radio today.
When listening to modern music, you might notice a single instrument play for an extended period. These solos have their roots in jazz improvisation. Improvisation is nothing more than a spontaneous melody. Jazz musicians structure their songs to allow for these improvised melodies. When you listen to an instrumental solo--whether guitar or keyboard--by a modern band, you are listening to a jazz concept.
Before jazz, most genres of music placed the notes of the melody on the pulse, also called the beat, established by the other instruments. Jazz music started placing long melodic sounds between the established beat quite regularly. This technique, called syncopation, gives the music the feeling of having the hiccups. Syncopation has become a standard tool for writing modern music.
To provide a support system for the melody, music composers created combinations of simultaneous sounds called harmonies. The preferred harmony for most pre-jazz composers was a series of three notes called a triad. Jazz musicians expanded on this concept by adding sounds to the triad. Musicians called the resulting harmony a chord. Each sound in the chord received a number based on its distance from the bottom sound, called the root. The most common sound to add to a triad was the seventh--the sound that is seven steps away from the root. Modern music adopted the use of both triads and chords with the seventh.
Composers arrange triads into patterns called progressions. At key points in the melody, the triads give the song a sense of forward movement ("progression"). Composers traditionally wrote progressions using only three or four different triads. Jazz musicians of the "Bebop Era" revolutionized music by creating progressions that used as many as seven different chords. While not as complex, modern music takes its cue from jazz and uses diverse progressions of four to five different chords.
Jazz music made the saxophone a popular instrument for modern bands. Invented in 1840, the saxophone was relegated to military concert bands until the advent of jazz, when it gained popularity for its unique combination of sound and projection.
Jazz musicians also were the first to develop the drum set. Before jazz, bands required one person each to play the snare and bass drums, the cymbals and the tom-toms. A jazz band relied on one person to play all the necessary drum instruments. Today’s modern band would not think of playing without a drummer behind a drum set.